Nick
I don't think you'll find off the shelf wheels/brakes at the 1.5 inch dia. EJF sells a 2 inch wheel/brake, If your serious about the C5 why not go to someone like Glennis or Serria and cet them custom made . There going to be big bucks, but just take a few more trips ,eat MRE's and use the perdiem for the wheels/brakes
If that option is no good just up the scale so you could use OFF the SHELF items.....
Semper Fi
Joe